Automatic parallax indicating means for twin lens reflex cameras with interchangeable objectives



United States Patent Inventor Mlchihiro Noguchi,

Tokyo, Japan Appl. No. 723,126

Filed April 22, 1968 Patented Nov. 17, 1970 Assignee Konica CameraCorporation Woodside, New York Priority Feb. 17, 1967, Nov. 10, 1967Japan 42/12,955 and 42/94,661

Continuation-in-part of Ser. No. 705,978, Feb. 16, 1968, abandoned.

AUTOMATIC PARALLAX INDICATING MEANS FOR TWIN LENS REFLEX CAMERAS WITHINTERCIIANGEABLE OBJECTIVES 10 Claims, 3 Drawing Figs.

0.8. CI 95/44, 95/42 Int. Cl G07b 13/12 Field of Search 95/44, 42, l 1,44A, 44B

.3 r i 2 x [56] References Cited UNITED STATES PATENTS 2,048,773 7/1936Baumgartner 95/44 3,029,720 4/1962 Leitz et al.. 95/44 3,356,003 12/1967Eckhardt 95/44 FOREIGN PATENTS 1,203,118 10/1965 Germany 95/44 PrimaryExaminer-Norton Ansher Assistant ExaminerRichard L. Moses Attorney-MeGlew and Toren ABSTRACT: A twin lens reflex camera with interchangeableobjectives include a photographic objective, a finder objective, and anindicator which indicates the parallax between the finder objective andthe photographic objective. A rod is movable parallel to the opticalaxis in accordance with adjustment of the photographic objective alongthe optical axis and operates a cam controlling the position of aparallax indicator. Each interchangeable objective has a pin or the likethereon correlated with its focal length, and the forward end of the rodengages this pin Patented Nov. 17, 1970 INVENTOR.

MICHIHIRO N0 GUCHI BY I flgw flaw ATTORNEYS CROSS REFERENCE TO RELATEDAPPLICATION This application is a continuation-in-part of copending US.Pat. application Ser. No. 705,978, filed Feb. 16, 1968, now abandoned,for AUTOMATIC PARALLAX INDICATING DEVICE FOR TWIN LENS TERCHANGEABLEOBJECTIVES.

BACKGROUND OF THE INVENTION As is well known, twin lens reflex camerashave two optical axes spaced from each other, one being the optical axisof the photographing objective and the other being the optical axis ofthe finder objective. This results in parallax between an image in thefinder and a picture taken by the photographic objective. The amount ofsuch parallax depends on the distance to an object to be photographedand also on the focal lengths of interchangeable objectives.

With respect to twin lens reflex cameras having fixed objectives, therehave been various proposals to provide an interlocking mechanism betweenfocusing means and a parallax indicator, for obtaining, on a focusingscreen, and indication of a correction for parallax, which varies withthe distance to the object to be photographed.

However, with twin lens reflex cameras with interchangeable objectives,provision must be made to accommodate for the variation of the rate ofchange of the parallax, not only with the distance to the object to bephotographed but also with the differing focal lengths of theinterchangeable objectives.

Inasmuch as a parallax indicator is mounted on the camera body and anexchangeable objective is mounted on a movable part of the camera, ithas been difficult to provide the possibility that the rate of change ofparallax can be adjusted under any situation. A solution has beenproposed in Japanese Pat. Publication No. 24155/1964, and this proposalis to vary the rate of change as objectives are interchanged. However,the proposal has the disadvantage that exchange of objectives must beeffected at a particular position of the objectives, and that manualadjustment is required to bring the rate of change of the parallax intocorrespondence with the focal length of the new objective.

SUMMARY OF THE INVENTION This invention'relates to twin lens camerasand, more particularly, to novel apparatus for automatic indication ofparallax in twin lens reflex cameras having interchangeable objectives.

In accordance with the invention, the apparatus includes a memberpivoted to an objective-carrying component which is movable parallel tothe optical axis of the camera. One end of this member is in contactwith a pin on the objective carrying component, and the other end of themember has a cam surface. Another member is pivoted on the camera bodyand has one end in contact with the cam surface, with the other end ofthe other member serving to indicate, within a finder, the amount ofparallax. The pin engaged by the member pivotally mounted on theobjective-carrying component is respective to a particularinterchangeable lens, corresponding, for example, to the focal length ofthe respective interchangeable lens.

The parallax indicator can be, for example, an indicating needle movablealong or beneath a transparent plate, or it can be a parallax correctionframe movable along a focusing screen and connected to the end of themember which is pivoted on the camera body.

An object of the invention is to provide an apparatus for alwaysindicating the correct value of the parallax when an objective isadvanced or retracted during focusing.

Another object of the invention is to provide such an apparatus, fortwin lens reflex cameras, which permitsfree interchange of objectivesindependently of the relative extension or retraction of the objectives.

CAMERAS WITH IN- A further object of the invention is to provideapparatus, for twin lens reflex cameras, in which the rate of change ofthe parallax value is adjusted automatically as objectives havingdifferent focal lengths are interchanged.

Still another object of the invention is to provide a parallaxindicating apparatus for twin lens reflex cameras which is simple inconstruction and reliable in operation.

BRIEF DESCRIPTION OF THE DRAWINGS For an understanding of the principlesof the invention, reference is made to the following description oftypical embodiments thereof as illustrated in the accompanying drawings.

In the Drawings:

FIG. 1 is a graphical illustration of the fundamental principle ofoccurrence of parallax in twin lens cameras, having a finder objectiveand a photographic objective whose optical axes are space from eachother;

FIG. 2 is aperspective view of the essential parts of a twin lens reflexcamera embodying one form of parallax indicating apparatus in accordancewith the invention; and

FIG. 3 is a somewhat schematic side elevation view illustratingessential parts of a twin lens camera incorporating another form ofparallax indicating apparatus in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, themagnitude of parallax is v designated as c, the spacing between theoptical axes of upper and lower lenses is designated of the objectivesis designated forward focal point and an designated by x, and the focald,the magnitude of movement by x,the distance between the object to bephotographed is length is designated by f. From Since d is constant fora camera, it follows that the magnitude of c is directly proportional tox and inversely proportional to f. Thus, a parallax indicating mechanismmay be obtained by using a linear cam for interconnecting a parallaxindicator with an objective-moving mechanism, and by causing theinclination of the linear cam to be varied in inverse proportion to thefocal length.

In other words, the linear cam may be provided on a component which ismoved with the objectives, and the inclination of the linear cam may bevaried as the focal length of the objectives is changed, due tointerchange of objectives. On the camera body, there is arranged amember for movement with contact with the cam, so that this member, oran element attached thereto, provides an indication of the magnitude ofparallax. The present invention is based upon the above principle, andtwo embodiments thereof will be described with reference to FIGS. 2 and3.

Referring first to FIG. 2, an interchangeable objective mount isindicated at l as arranged for mounting, on the camera, a finderobjective 2 and a photographing objective 2. Mount 1 is mounted on anobjective-moving plate 3 having a rack 4 extending therefrom and engagedby a pinion 5 which may be rotated by a knob 5'. It will be noted thatrotation of pinion 5 by knob 5' effects displacement of theinterchangeable objective mount 1 parallel to the optical axes of theobjec tives.

A linear cam 6 is pivotally mounted at 8 on the objectivemoving plate 3,and has an end 7 engaged with a pin 9. Pin 9 is secured to objectivemount 1 for varying the inclination of f linear cam 6, and the pins 9 oninterchangeable objectives have different lengths corresponding to thefocal lengths of the respective objectives. It will be noted that thefree end of pin 9 abuts against the end 7 of linear cam 6 to vary theinclination of cam 6 in accordance with the focal length of theobjectives mounted on a particular mount 1.

A lever 10, carrying a pin 11 at its lower end, is pivotally mounted onthe camera body by pivot 12. Pin ll engages linear cam 6, and the otherend of lever 10 is forked to receive and move an indicator or needle 14indicating the magnitude of parallax on a focusing screen 13. A spring15 surrounds pivot 12 and has one end secured to the camera body and theother ends secured to lever 10 to bias lever 10 to rotatecounterclockwise. By virtue of the bias exerted by spring 15, actingthrough the pin 11 on cam 6, linear cum 6 tends to rotate clockwiseabout its pivot 8 so that its end 7 is urged against pin 9. A reflectingmirror isindicated at 16, and directs light from finder objective 2 tofocusing screen 13.

For focusing of the camera, pinion Sis rotated by knob to move plate 3parallel to the optical axes, through'the medium of rack 4, therebymoving mount 1. Depending on the direction in which rack 4 moves, linearcam 6 is bodily moved in one direction or the other so that pin 11causes lever to rotate about its pivot 12 either against the bias ofspring 15 or under the bias ofspring 15. I

As mentioned above, the magnitude of parallax is proportional to themagnitude of movement of the lens systems, so that needle 14 alwaysprovides a correct indication of the magnitude of parallax when theinclination of linear cam 6 is maintained at a proper value inaccordance with the respective focal lengths of the interchangeableobjectives 2 and 2'. When theinterchangeable objective mount 1 isreplaced by another mount 1, mounting objectives having a differentfocal length, the mount 1 of the newly positioned objectives has a pin 9of a length corresponding to the focal length of the objectives, andproviding as inclination to linear cam 6 corresponding to the focallength of the new objectives.

Although, in the above description, it is stated that pins 9 areselected to have lengths corresponding to the respective focal lengthsof the lens systems used, the inclination oflinear cam 6 may becontrolled by means other than the lengths of pins 9, such as bychanging their shape or mounting position. Pin 11 on lever 10 movesalong a circular path concentric with pivot 12, so that lever 10 doesnot provide a precisely propor tional motion. However, the length orshape of lever 10 may be selected so that any resulting error may beheld within reasonable tolerances for practical purposes. Alternatively,linear cam 6 may be changed to a slightly curved cam. When highprecision is required, known means may be utilized to convert circularmotion into linear motion.

Referring to FIG. 3, which illustrates an alternative embodiment of theinvention, a lens mount is indicated at 21 as mounting a finderobjective 22 and a photographing objective, the latter not being shownfor reasons of simplicity. Mount 21 is supported on an objective-movingplate 23 which has a rack extension 24 engaged by a pinion 25 which maybe rotated in the same manner as mentioned for FIG. 2, in focusing thecamera. Rotation ofpinion 25 causes mount 21 to move parallel to theoptical axes of the finder objective and the photo graphic objective.

A focusing screen is illustrated at 26 as arranged on camera body 27 toextend at right angles to the optical axis of finder objective 22. Alinear cam 28 is pivotally mounted, at pivot 30, on objective-movingplate 23, the mounting portion of cam 28 being indicated at 29. Atransmission rod 31 is slidably supported by objective-moving plate 23,and rod 31 engages a pin 32 secured to exchangeable objective mount 21,for correction of the initial inclination of linear cam 28. The pins 32on different exchangeable objective mounts 21 have different lengths,depending on the focal length of the respective objectives.

The opposite end of rod 31 engages an end 28' oflinear cam 28, for thepurpose of varying the initial inclination of cam 28.

A lever 33 is pivoted at one end to the camera body 27 at pivot 34, andcarries a pin 35 which engages linear cam 28. The opposite end of lever33 is formed with an outwardly opening slot 36. A parallaxcorrectionframe 37 is arranged adjacent focusing screen 26, and a pin 38 attachedto frame 37 is engaged in slot 36-of lever 33. Parallax correction frame37 is guided in one or more guide rails 39, for displacement parallel tofocusing screen 26. A spring 40 has one end secured to lever 33, and itsopposite end abuts camera body 27, spring 40 biasing pin 35 carried bylever 33 into engagement with linear cam 28.

During focusing of the camera, pinion 25 is rotated to move rack 24which, in turn, causes objective-moving plate 23 to move parallel to theoptical axis of objective 22. At the same time, linear cam 28 pivotallymounted on plate 23is bodily moved in a direction corresponding to thedirection of movement of plate 23. Thereby, due to engagement betweenpin 35 and cam 28, lever 33 is turned either in the direction of bias oraction of spring 40 or in opposition to the bins of spring 40. Thiseffects displacement of parallax correction frame 37.

As previously mentioned, the magnitude of parallax is proportional tothe magnitude of movement of the objective, so that frame 37 indicatesthe parallax correctly in focusing screen 26 when'the inclination oflinear cam 28 is adjusted to the proper value corresponding to the focallength of objective 22. When exchangeable objective mount 21 is replacedby another objective mount carrying objectives of a different focallength, the pin 32 on'the new mount will have a length such as toprovide a proper inclination to linear cam 28.

In the embodiment shown in FIG. 3, lever 33 is pivoted at one end tocamera body 27 by means of pivot 34. However, it may be pivoted adjacentits center to camera body 27, so that one end carries pin 35 engaginglinear cam 28 and the other end engages parallax correction frame 37.Also, while pins 32 on various objective mounts 21 have been describedas selected to have lengths corresponding to the respective focallengths, to provide a proper initial inclination to linear cam 28 inaccordance with the respective focal length, the inclination of linearcam 28 may be controlled by other means such as by variation of pinshape or mounting position on objective mounts 21. Although the movementof pin 35 on lever 33 follows a circular path concentric with pivot 34,and thus may not have a correct proportional motion under certaincircumstances, the length or shape of lever 33 may be changed suitablyso that any resulting error is negligible for all practical purposes.Alternatively, linear cam 28 can be changed to a slightly curved cam. Asmentioned in connection with the em bodiment of HG. 2, when highprecision is required, known means may be used to convert circularmovement to linear movement.

Thus, in accordance with the invention, interchangeable objective mountscarrying objectives of different respective focal lengths, need only beprovided with inclination controlling pins of lengths corresponding tothe respective focal lengths in order to provide proper inclination tothe linear cam. Thereafter, an automatic indication of the correctmagnitude of parallax is obtained when such objective mounts areinterchanged on the objective-moving plate.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

lclaim:

1. In a twin lens camera having a camera body, interchangeable objectiveassemblies, an objective assembly mounting member movable along saidbody parallel to the optical axis of mounting member for bodily movementwith the latter during focusing, and .engageable with the abutment of anobjective assembly mounted on said mounting member for movement to anorientation corresponding to the focal length of said mounted objectiveassembly; cam follower means movably mounted on said camera body andengaged with said linear cam means for movement by the latter duringfocusing movement ofsaid mounting member parallel to the optical axis;and a parallax indicator connected to said cam follower means andmovable thereby along said focusing screen.

2. In a twin lens camera, apparatus for indicating the magnitude ofparallax between the twin lenses, as claimed in claim I, in which saidabutments constitute pins each having a length corresponding to therespective focal length of the associated objective assembly.

3. In a twin lens camera having a camera body, interchangeable objectiveassemblies, an objective assembly mounting member movable along saidbody parallel to the optical axis of the camera, and a focusing screen,apparatus for indicating the magnitude of parallax between the twinlenses comprising, in combination, an abutment on each objectiveassembly having a parameter coordinated with the respective focal lengthof the associated assembly; linear cam means movably mounted on saidmounting member for bodily movement with the latter and engageable withthe abutment of an objective assembly mounted on said mounting memberfor movement to an orientation corresponding to the focal length of saidmounted objective assembly; cam follower means movably mounted on saidcamera body and engaged with said linear cam means for movement by thelatter during focusing movement of said mounting member parallel to theoptical axis; and a parallax indicator connected to said cam followermeans and movable thereby along said focusing screen; said abutmentsbeing pins each having a position on its respective objective assemblycoordinated with the respective focal length of the associatedobjectiveassembly.

4. in a twin lens camera having a camera body, interchangeably objectiveassemblies, an objective assembly mounting member movable along saidbody parallel to the optical axis of the camera, and a focusing screen,apparatus for indicating the magnitude of parallax between the twinlenses. comprising, in combination, an abutment on each objectiveassembly having a parameter coordinated with the respective focal lengthof the associated assembly; linear cam'means movably mounted on saidmounting member for bodily movement with the latter and engageable withthe abutment of an objective assembly mounted on said mounting memberfor movement to an orientation corresponding to the focal length of saidmounted objective assembly; cam follower means movably mounted on saidcamera body and engaged with said linear cam means for movement by thelatter during focusing movement of said mounting member parallel to theoptical axis; and a parallax indicator connected to said cam followermeans and movable thereby along said focusing screen; said linear cammeans being a lever pivotally mounted on said mounting member and havinga relatively elongated substantially linear cam'surface, said lever,responsive to engagement with an abutment on a mounted objectiveassembly, being pivoted to an angular position corresponding to thefocal length of said mounted objective assembly.

5. In a twin lens camera, apparatus for indicating the magnitude ofparallax between the twin lenses, as claimed in claim 4, in which saidcam follower means includes a lever pivotally mounted on said camerabody and having said parallax indicator connected to one end thereof,and a cam follower on said lastnamed lever engaged with saidsubstantially linear cam surface.

6. In a twin lens camera, apparatus for indicating the magnitude ofparallax between the twin lenses, as claimed in claim 4, in which saidlever is 'a two-arm lever pivoted on said mounting member intermediateits ends, one arm of said lever engaging an abutment and other armhaving said substantially linear cam surface.

7. In a twin lens camera, apparatus for Indicating the magnitude ofparallax'between the twin lenses, as claimed in claim 4, in which saidlever is a two-arm lever with one arm being formed with saidsubstantially linear cam surface; and a transmission rod slidablymounted on said mounting member and having one end engaged with theother arm of said lever and its opposite end engageable with theabutment of a mounted objective assembly.

8. ln twin lens camera, apparatus for indicating the magnitude ofparallax between the twin lenses, as claimed in claim 6, in which saidcam follower means comprises a second lever. pivotally mounted;intermediate its ends, on said camera body, a pin at one end of saidsecond lever engaged with said substantially linear cam surface, meansbiasing said second lever to maintain said pin engaged with saidsubstantially linear cam surface, and a slot in the opposite end of saidsecond lever engaged with said parallax indicator to move the latteralong said focusing screen.

9. In a twin lens camera, apparatus for indicating the mag nitude ofparallax between the twin lenses, as claimed in claim 7, in which saidcam follower means comprises a second lever pivotally-mounted at one endon said camera body, a pin carried by said second lever intermediate itsends and engaged with said substantially linear cam surface, meansbiasing said second lever to maintain said pin engaged withsaidsubstantially linear cam surface, and a slot in the opposite end of saidsecond lever receiving an element connected to said indicator fordisplacement of said indicator relative to said focusing screen. I

10. In a twin lens camera, apparatus for indicating the magnitude ofparallax between the twin lenses, as claimed in claim 9, in which saidindicator is a frame movable parallel to said focusing screen; and guidemeans guiding movement of said frame.

